Recovery of oxidation inhibitors



March 9, 1954 J. G. LlLLARD RECOVERY OF OXIDATION INI-IIBITORS Firedoct. 19, 195o 2 Sheets-#Sheet l ALCOHOL STORAGE 'ATE R TETRHYOROFUIFURYL ALCOHOL INTERUEOITE EXTRAOT INVENTOR. James 6. Lil/ord,

March 9, 1954 A 1 G, ARD 2,671,753

RECOVERY OF OXIDATION INHIBITORS l Filed Oct. 19, l1950 2 Sheets-Sheet 2OXID TION v INHIBITUR ll-LIGHT SOLVENT il M l TETRAHYDRUFURFURYL I4ALCOHOL STORAGE j ACETONE STORGES' sPEfH'V nu su meren 124 Llenr "2'saLvsNr f iI f | serrLsn 122 i l 5 N20 J2 WA TER FRGTION INVENTOR. JamesG. Lil/ard,

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ATTORNEY.

Patented Mar. 9, 1954 `UNITED STATES PATENT OFFICE RECOVERY OF OXIDATIONINHIBITORS James G. Lillard, Baytown, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation of Delaware Application october 19, 195o, serial No.190,915

7 Claims.

The present invention is directed to a method for recovering anoxidation inhibitor from solvent extracts of lubricating oil fractions.More particularly, the invention is directed to the production of anoxidation inhibitor from a solvent;

fraction, for example, a Mid-Continent lubricating oil fraction, with asolvent comprising tetrahydrofurfuryl alcohol or with a solventcomprising tetrahydrofurfuryl alcohol and acetone. The phenol extract isadmixed with the tetrahydrofurfuryl alcohol solvent under conditions toprovide a ratio of tetrahydrofurfuryl alcohol to solvent extract in thepreferred range between 1:1 and 4:1. A small amount of water, such as upto about 3% based on the solvent may be added to increase the solventselectivity. At temperatures in the range from 20 to 100 C. and atpressures ranging from to 25 pounds greater than the vapor pressure ofthe solvent, the admixture of the solvent extract and solvent formsstripping of the solvent from the hydrocarbon extract phase. Thesolvent-free hydrocarbon extract phase recovered by either of the aboveprocedures is then suitable for use as an oxidation inhibitor. Theoxidation inhibitor may suitably be added to oxidation susceptiblelubricating oil fractions such as those obtained from Coastal crudes andthose having a naphthene base.

The present invention will be further illustrated by reference to thedrawing in which:

Fig. I is in the form of a diagrammatic iiow sheet illustrating one modeof practicing the present invention and Fig. II is in the form of a owsheet illustrating another mode of practicing the present invention.

Referring now to the drawing, and irst to Fig. I. numeral I I designatesan extraction zone which is designed to allow countercurrent extractionof hydrocarbon oils. Extraction zone II is understood to includeinternal baling equipment such as bell cap trays and contact equipmentto allow intimate contact between immiscible liquids. It will beunderstood that extraction zone Il is also provided with means forinducing reflux such as are well known in the solvent extraction art.Leading into extraction zone Il is line I2 by way of which there isintroduced thereto a feed which for the purposes of this description isa, phenol extract of a Mid-Continent lubricating oil fraction. At timesit may be desirable to admix the feed with a paraiiinic hydrocarbonbefore it is introduced into the extraction zone, and such a vlighthydrocarbon may be introduced through iniet line IIJ into the feedpassing through line I2. Where a phenol extract of `MidContinentlubricating oil fraction is used as feed, the par'- aiiinic hydrocarbonmay be added thereto in an amount within the range from 10% to 150%based on said phenol extract. There is introduced into extraction zoneIl from storage tank I 3 tetrahydrofurfuryl alcohol which is dischargedfrom tank I3 by line I4 and thence by line I5 into extraction zone II.Conditions are adjusted in extraction zone il to maintain a temperaturein the range between 20 and 100 C. such that a liquid phase ismaintained therein. Pressure may be in the range from 0 to 25 poundsgreater than the vapor pressure of the tetrahydrofurfuryl alcohol. Underthe conditions in extraction zone I I, which preferably includes themaintenance oi a tetrahydrofurfuryl alcohol to phenol extract ratio inthe range between 1:1 and 4:1, there is formed therein a raiiinate phaseand an extract phase. The extract phase by virtue of the nature of thetetrahydrofurfuryl alcohol separates in the lower portion of zone II andthere may be admixed therewith by way of line I6 controlled by valve I'Ia small amount of water such as up to about 3% by volume based on theoriginal tetrahydrofurfuryl alcohol. The water-containing extractdischarges from extraction zone Il by line I8 and may be introducedthereby into a solvent stripping zone I9 which is provided with aheating means illustrated by steam coil 20 wherein temperatures andpressure are adjusted therein to allow the removal from stripper I 9 ofwater by line 2l and tetrahydrofurfuryl alcohol by way of line 22 whichreturns the tetrahydrofurfuryl alcohol to storage tank I3. The oxidationinhibitor is withdrawn from stripper I9 by line 23 for addition tolubricating oils susceptible to oxidation. Stripping zone i9 ispreferably operated at reduced pressures as low as l0 mm. mer- .euryabsolute to prevent alcohol degradation.

The ranate phase from extraction zone H discharges by line 24 controlledby valve 25 into a stripping still 26 which is similar to strippingstill I9 and is provided with a heating means illustrated by coil 21wherein conditions are adjusted in stripper 2S to remove overheadtherefrom water by line 23 and as a side stream tetrahydrofurfurylalcohol by line 29 which connects into line 22 and allows return of thetetrahydroi'urfuryl alcohol to storage tank I3. The stripped` raffinatedischarges from stripper 25 by line 33 controlled by valve 3! into line32 and` thence intol a second extraction zone 33 wherein the raiiinateis subjected to re-extraction with acetone introduced thereto by line 34from. acetone storage tank 35.

Extraction zone 33 is similar to extraction zone Il and is provided withcontacting equipment to insure intimate contact between inimiscibleliquids. Extraction zone 33 is also provided with means for inducingrefiux therein. The temperature conditions in extraction zone 33 are. inthe range between U and' 75 C. while pressures may range from 0 to 30'pounds per square inch gauge. The amount of acetone which is em'- ployedto contact the raihnate in extraction zone 33 may range from a ratio ofl to l to d' to. l of acetone to raffinate. Under conditions obtainingin extraction zone 33 a second ramnate and a second extract phase areformed'. The second.- ary extract is withdrawn from extraction zone 33by line 35 controlled by valve 3l* and introduced thereby into astripping still 38 which, similar to stripping stills i3 and 33, isVprovided with a heating unit. illustrated by coil 39 wherein temperatureand pressure conditions are maintained to remove overheadV byY line 43which connects into line 4I acetone which is returned; by line di andbranch line 42 to acetone storage The stripped secondary extractdischarges from stripper 38 by line 43 controlled by valve 44 and may berecycled to line I2 by way of line 43 controlled by valve 46 orV may bedischarged in part by opening valve 4T forV withdrawal oftheintermediate extract froxn the system.

Alternatively, the extract withdrawn by line 36 from extraction zone 33may by-pass stripper 33 by closing valve 3'! in line 33 and thusallowing the extract to be routed by line 48 controlled by valve 43 toline 43 and thence by line 45 for admixture with the phenol extract inline i2.

The rainate from secondary extraction zone 33 discharges therefrom byline 53 and is introduced thereby into a stripping zone I which, similarto the other stripping stills, is provided with a heating meansillustrated by steam coil 52 for adjustment of temperatures andpressures therein to allow removal from stripper 5I by line 4I acetonewhich is discharged by lines I and 42 into acetone storage 35. Since theramnate withdrawn from extraction zone II and second extraction zone 33contains tetrahydrofurfuryl alcohol, the acetone stripped raffinate isdischarged from stripper 5I by line 53 and routed by line 54 controlledby valve 35 into stripping zone 56 which is similar to the otherstripping zones and is provided with a heating means illustrated by asteam coil 57 to allow recovery of the tetrahydrofurfuryl alcohol fromthe raffinate by line 53 which connects into line 22 and conducts thetetrahydrofurfuryl alcohol back to storage tank i3 for re-use in theprocess. rEhe stripped rainate is withdrawn from stripper 53 by line 53controlled by valve 30 for use as may be desired.

As an alternative mode of practicing the invention, a mixture oftetrahydrofurfuryl alcohol and acetone may be employed as a solvent.Under these conditions the ratio of tetrahydroiurfuryl alcohol toacetone may range up to equal volurnes of tetrahydrofurfuryl alcohol toacetone. For purposes of this description it is assumed that an equalVolume mixture of tetrahydrofurfuryl alcohol', and acetone is introducedinto extraction zone II by way of line I5, the acetone being withdrawnfrom storage tank 6I by line 62 controlled by valve 63. It is to beunderstood `that instead of providing an extra storage tank 6I foracetone that storage tank 35 may be used therefor, but for purposes ofthis description two storage. tanks are provided. In this operation thefiow is identical to that described before with the exception that theextract withdrawn by line I8 is discharged by branch line 64 controlledby valve, 65A into stripping zone 63 which, like the other strippingzones, is provided with a heating means illustrated by steam coil 6l'for adjustment of temperature and pressure conditions therein. When thismode is employed, it isv understood, of course, that valve 63 in lineVWis in a closed position. Removed overheadfrom stripper 55 by line 69 isa stream of acetone which is discharged into storage tank 35 by way ofline 42. The acetone-free extract is withdrawn from stripper 66 by line'E3 controlled byY valve- T'I into line i8 and dischargedv thereby intoline F3" for removal of water and tetrahydrofurfuryll alcohol as hasbeen described, and forV recovery of the oxidation inhibitor by line 23.

The rafnate may be withdrawn from extraction zone II by line 24 anddischarged into line 32 for introduction into second extraction'zone 33as has been described, stripping zone 2I5v being by-passed by closingoii` valve 25 inline 24 and valve 3l in line 33, valve 'I2A in line 32being opened to allowv passage of the rafilnate directly into extractionzone 33. The ow thereafter is identical with that described before withthe extract either lay-passing stripper 38 or flowing by line 48 andline 43 and thence by line 45 back into feed line I2.

Although stripping techniques are generally preferred for separation ofhydrocarbon extract and solvent, water washing procedures may beemployed. The solvent extract, for example. may be admixed withsuiiicient water, such as 15% or higher based on the extract phase tocause separation of hydrocarbon and solvent. rThe hydrocarbon layerlafter separation, may be water washed to remove traces of solventremaining therein;

Referring now to Figure II, another mode for practicing the presentinvention is here illus'- trated.

Irl Fig. II, extraction zone III corresponds to extraction zone II ofFigure I. Storage tank I3, used for storing tetrahydrofurfuryl alcohol,and storage tank 62, used for storing acetone, and the lines I4, I5, S2and valve 63 are identical to the corresponding units of Fig. I. Feed,such as a phenol extract of a Panhandle medium motor distillate, isintroduced by inlet line II2 into extraction zone IH. In extraction zoneIII, a. raffinate phase and an extract phase are formed, the extractseparating tothe lower portion of zone I II and being withdrawn throughline IIB, while the raiiinate phase is withdrawn from extraction zone HIthrough outlet line I24. Into the stream of extract phase in line IIBthere is introduced a low viscosity para'inic solvent by means of inletline I I 4.1 The parafilnic' solvent is added'inv an amount sumcient toreduce the The aqueous alcohol layer is with- The hydrocarbon layer iswithdrawn from settler |23 through` line |25 and passed into vessel |25,where it is washed with water introduced through inlet line |21 with aspent Wash water withdrawn through outlet line |28. The washedhydrocarbon is then passed from washing vessel |25 through line |29 tostill |30 where the low viscosity paraiiinic solvent is removed asoverhead through line |3| and the oxidation inhibitor is withdrawnthrough line |32.

It will be understood that various types oi auxiliary equipment, forexample, such as that required for the recovery of solvent, will bedesirable in the operation of the method illustrated in Fig. II, but forthe purpose of simplifying the drawing and the description, suchequipment has not been shown.

From the foregoing description and drawing, it will be seen that severalmodes of operation are provided wherein an oxidation inhibitor may berecovered by extracting a solvent extract of a lubricating oil fractionwith tetrahydrofurfuryl alcohol.

The invention will be further illustrated by the following runs: In thefirst run 450 volumes of a lphenol extract of dewaxed Panhandle mediummotor distillate were admixed with approximately equal Volumes oftetrahydrofurfuryl alcohol at 24 C. and at atmospheric pressure. Undervthese conditions an extract layer was separated and diluted withapproximately equal volumes (500 parts) of a paraflinic solvent such aspetroleum ether to reduce the viscosity of this layer. Water was thenadded to the admixture of extract and paraffnic solvent in an amount ofapproximately based on the extract layer. 'Ihe purpose of the additionof water was to reduce the solvency of the tetrahydrofurfuryl alcohol inthe hydrocarbon and cause phase separation. The resulting hydrocarbonlayer was then removed, washed with water several times to remove allthe tetrahydrofurfuryl alcohol, dried and then distilled to striptherefrom the petroleum ether. Approximately llvolume per cent of anoxidation inhibitor was recovered. Physical and chemical inspection ofthe phenol extract charged to the operation and the raffinate which wasrecovered by water washing, drying and stripping similar to theaforementioned technique is compared in the following table with thecharacteristics of the tetrahydrofurfuryl al- A 6. From the foregoinginspection characteristics it will be seen that the tetrahydrofur'furylalcoholv extract has a much higher carbon-hydrogen weight ratio thaneither the phenol extract charge stock or the raiiinate therefrom.

Various amounts of the tetrahydrofurfuryl alcohol extract were thenadded to an unstable Coastal lubricating oil and the blends were oxid-lized under identical conditions in an accelerated laboratory oxidationtest. The relative increase in viscosity was taken as a measure ofdegree of oxidation. The data obtained on these oxidation runs are shownin comparison with similar data. obtained for blends of the unstableCoastal lubricating oil with the original phenol extract charge stockand with silica gel extracts of the phenol extract in varyingpercentages. An oxidation index, which is the product of the ratio ofthe per cent viscosity increase of the sample to therper cent viscosityincrease of .the standard times 100, was calculated for each sample forobtaining relative oxidation characteristics. A lower oxidation indexindicates greater resistance to oxidation. These results are given inTable II:

Table II Viscosity at F. Percent Oxidw Additive and ConcentrationIirxllcssf tion 2 Initial Oxicosity Index dized None (Standard) 577 1,650 186 100 5%-Total Phenol Extract 615 950 55 30 2%-20.6 to 20.9 1 -A577 l, 579 173 93 2%-55.8 t0 57.1 577 1, 403 143 77 1%-97.8 t0 98.3 A577 l, 125 95 5l. 1%-Tetrahydrofurfury Alcohol Extract 577 886 53. 5 298%-Tetrahydrofurfuryl Alcohol Extract 577 S88 54 295%-Tetrahydroiurfuryl Alcohol Extract 57 7 721 25 13 UniuhlbitedFinished Panhandle Medium Motor Oil 485 583 20 11 l Volume percentextract-,from silica gel extraction of the phenol extract.

2 Percent Vis. Increase of Sample Percent Vis. Increase of Standard Theoxidation test employed is used to compare the change in properties inoil after subjecting it to xed oxidation conditions. Usually it isdesirable to compare the oil to be tested to a standard oil subjected tothe same test. The test is carried out as follows:

Oxidation of an oil sample is carried out in a 200 cc. glassthree-necked round bottom ask. The central neck of this flask is 5 cm.long and has an inside diameter of 3 cm. The two opposed side necks are6 cm. long and 1.5 cm. inside diameter, and are situated at a 30 anglewith the central neck, perpendicular to the surface of the sphericalflask. The stirrer is a glass rod 0.5 cm. in diam'- eter, entering theflask through a glass tube bearing held in place by a rubber stopper inthe central neck, with two glass blades 1.0 cm. long by 0.7 cm. widewelded to opposite sides of the bottom end of the glass rod at a 30angle with .the vertical. The stirrer is driven by a `1'750 R. P. M.motor connected to the stirrer by a rubber tubing coupling. The bladesof the stirrer are situated about 0.5 cm. from the bottom of the flaskand spin in such a direction that their propeller-like action circulatesthe oil to the bottom of the ask, up along the sides of the iiask, backto the center of the flask, and down to the stirrer Ablades again. Aconsiderable .amount of air issuckedfdown with the descending oil andintimately contacted with phenol extract.

it by the action 'of the stirrer. .A thermometer .Well cm. longer and1.0 cm. inside diameter is situated in one side of the lnaskequiclistantfrom the tivo side arms. During the oxidation the nasi: is abouttwo-thirds immersed in an oil bath maill- .tained at 375 F. Thetemperature of 'the oil in the `:flask is usually 5 to 10 F. below thetemperature of the oil bath.

' 'The oxidation test is carried out in a specially constructed nask by'stirring 100 cc. of the sample in the presence of air for sixteen hoursat 375 F. At the end or" 'that time the flask is removed from the oilbath and tests obtained on the oxidized oil.

The data .presented in Table Il show that the vtetra-hydrourul'ylalcohol extract is effective in stabilizing an cxidizable Coastallubricating oil. Furthermore, it will be seen that the oxidizableCoastal lubricating oils, to which the oxidation inhibitor has beenadded in an amount from 3 to 5 by volume, approach in quality, asmeasured by .the oxidation index, the quality of the original Panhandlemedium motor oil from which the `phenol extract was obtained.

While one of the examples shows the dilution of the extract layer. witha, parainic solvent, it may be desirable to dilute the solvent extract,such as phenol extract, which is charged to the process with a parainicsolvent to reduce the viscosity thereof and to facilitate the separationinto phases on extraction with tetrahydrofurfuryl alcohol. Illustrativeof paraiiinic hydrocarbons which may be used to dilute the solventextract or the tetrahydrofurfuryl alcohol extract are :Dentaria hexane,heptane, octane, nonane and the like, including isomers thereof. Ratherthan use a Substantially pure parafnic hydrocarbon,

it may' be desirable to use a paramnic hydrocarfbon fraction boiling inthe range from about 100 1i'.l up to about 300 F.

As another example of the practice of the present invention, atetrahydrofurfuryl 'alcohol extract obtained in a single stage extractas described previously was rie-extracted with 200 volume per cent oftetrahydrofurfuryl alcohol with 1% by volume of water injection and anextract having a refractive index 11.52 of 1.5189 lwas ob- :alcohol toall acetone. Solvent mixtures containing from 20 to 9% by volume ofacetone were Ihiglrlly ellicient in rejecting materials of lowerrefractive index into the rail'lnate, While the tetrahydrofurfulylalcohol alone with Water injection as previously described was highlyselective in concentrating highly refractive index matenais.

The invention has been described and claimed with respect to extractinga phenol extract of a lubricating oil fraction with a solvent comprisingtetrahydrofurfuryl alcohol. While a phenol extract is preferred as thecharge stock, other ,solvent extracts of 'lubricating oil fractions maybe used. For example, furfural extracts of lubrieating oil fractions maybe used in lieu of a Similarly, extracts of lubricatiner oil Vfractionsproduced by extracting lubrieating' oil fractions with solventscomprises liquid "sulfur dioxide, nltrobenzene, trichloroetliylena filChlorex, -chlorophenolg 'cresylic acid. pyridine and the like. As ageneral statement, it may be said that the solvent extract which forms afeed stock for the process of the present invention may be an extract ofa lubricatingr oil produced by sole vent extracting same with a solventwhich has a preferential selectivity for non-parafnic constituents. Forexample, the solvent will take into solution therein substantiallynon-parafllnic constituents and Will reject the substantially parat'-iinic constituents. It may be further said that the solvent extract ofthe lubricating oil fraction forming 'a feed stock 'of the presentinvention should be a Solvent extract obtained by extractin'g 'alubricating oil fraction 'With a solvent other 'than that comprisingtetrahyd-rofurfuryl alcohol.

The nature and objects of the present invention having been completelydescribed and illustrated. what I Wish to claim as new and useful and tosecure by Letters Patent is:

l. A method for producing an oxidation inhibitor suitable for use inlubricating oil which comprises the steps of admixing a solventcomprising tetrahydrofurfuryl alcohol 'with a phenol extract 'of aPanhandle medium motor distillate fraction 'in an amount and underconditions of temperature and pressure sufcient to cause formation of asecond extract phase and a raffinate phase While maintaining a liquidstate, separating said phases, removing said alcohol from said secondextract phase, and recovering substantially alcohol-free hydrocarbonsfrom said second extract phase suitable for 'use as an oxidationinhibitor.

2. A method for producing an oxidation inhibitor suitable for use inlubricating oil which comprises the steps oi admixing a solventcomprising tetrahydrofurfuryl alcohol with a phenol extract of 'aPanhandle medium motor distillate fraction an amount and underconditions of temperature and pressure suiiicient to cause formation cfa second extract phase'and a. raf"- ilnat'e 'phase While maintaining aliquid state, separating said phases, admixing the extract phase With alow viscosity paraninic solvent in an amount suilicient to reduce theviscosity thereof, adding to the admixture of the extract phase and 10Wviscosity para-linie solvent a sufficient amount 'of water to reduce thesolvency of the alcohol in said extract phase and to form a hydrocarbonlayer and an aqueous alcohol layer, washing said hydrocarbon layer with`Water to remove alcohol therefrom, removing said low viscosity'parafnic solvent from said hydrocarbon layer by' distilling same andrecovering an oxidation inhibitor.

Y 3. A method for producing an oxidation inhibitor suitable for use inlubricating' oils which comprises the steps of countercurrentlycontacting in a solvent extraction Zone 'a phenolextract of a Panhandlemedium motor distillate fraction with a solvent comprisingtetraliydrofuifuiyl a1- cohcl in a ratio of alcohol to Solvent extracti'n the range between 1:1 and 4:1 at a temperature in the range between29 and 100 C. and at a pressure suiiicient to maintain liquid phaseconditions in said solvent extraction zone to form an extract phase anda rainate phase, adding sucient Water to said extract phase in saidextraction zone to reduce the solvency of said alcohol therein, removingsaid water-containing extract phase from said solvent extraction lache,

one distillinc said water-containing extract pliage 9 to remove waterand alcohol therefrom and to recover an oxidation inhibitor'.

4. A method for producing an oxidation inhibitor suitable for use inlubricating oils which comprises the steps of counter-currentlycontacting in a solvent extraction zone a phenol extract of a Panhandlemedium motor distillate fraction with a solvent comprisingtetrahydrofurfuryl alcohol and acetone, said alcohol and acetone beingpresent in said solvent in a ratio no greater than 1:1, in a ratio ofsolvent to solvent extract in the range between 1:1 and 4:1 at atemperature in the range between 20" and 100 C. and at a pressuresufficient to maintain liquid phase conditions in said solventextraction Zone to form an extractl phase and a raffinate phase, addingwater to said extract phase in said extraction zone in an amount inexcess of about 15% by Volume based on said extract phase, removing saidWater-containing extract phase from said solvent extraction zone anddistilling said Water-containing extract phase to remove Water andalcohol therefrom and to recover an oxidation inhibitor.

5. A method for producing an oxidation inhibitor suitable for use inlubricating oils which comprises the steps of counter-currentlycontactingr in a solvent extraction zone a phenol extract of a Panhandlemedium motor distillate fraction with a solvent comprising approxi"mately two volumes of tetrahydrofurfuryl alcohol and one volume ofacetone at a temperature of about 25 C. and at atmospheric pressure toform an extract phase and a raiiinate phase,

adding Water to said extract phase in said extraction zone in an amountin excess of about 15% by volume based on said extract phase, removingsaid Water-containing extract phase from said solvent extraction zoneand distilling said water-containing extract phase to remove acetone andaqueous alcohol therefrom and to recover an oxidation inhibitor.

6. A process in accordance with claim 5 in which the phenol extract isadmixed with a parainic hydrocarbon in an amount in the range from 10%to 150% based on said phenol extract prior to contacting with saidsolvent.

7. A process in accordance with claim 5 in which the rai'linate phase isadmixed with acetone under conditions to form a secondary rafiinate anda secondary extract phase and in which said secondary extract phase isadmixed with said phenol extract.

JAMES G. LILLARD.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,883,374 Hill Oct. 18, 1932 2,054,052 Govers Sept. 8, 19362,106,234 Bray Jan. 25, 1938 2,114,524 Egli Apr, 19, 1938 2,220,016Lyons Oct. 29, 1940 2,261,780 Whiteley Nov. 4, 1941 2,342,205 ManleyFeb. 22, 1944 2,412,823 Mayland Dec. 17, 1946

1. A METHOD FOR PRODUCING AN OXIDATION INHIBITOR SUITABLE FOR USE INLUBRICATING OIL WHICH COMPRISES THE STEPS OF ADMIXING A SOLVENTCOMPRISING TETRAHYDROFURFURYL ALCOHOL WITH A PHENOL EXTRACT OF APANHANDLE MEDIUM MOTOR DISTILLATE FRACTION IN AN AMOUNT AND UNDERCONDITIONS OF TEMPERATURE AND PRESSURE SUFFICIENT TO CAUSE FORMATION OFA SECOND EXTRACT PHASE AND A RAFFINATE PHASE WHILE MAINTAINING A LIQUIDSTATE, SEPARATING SAID PHASE, REMOVING SAID ALCOHOL FROM SAID SECONDEXTRACT PHASE, AND RECOVERING SUBSTANTIALLY ALCOHOL-FREE HYDROCARBONSFROM SAID SECOND EXTRACT PHASE SUITABLE FOR USE AS AN OXIDATIONINHIBITOR.